Genital mycoplasma infection and spontaneous preterm birth outcome: a prospective cohort study

Ureaplasma parvum infection induces inflammatory changes in vaginal epithelial cells independent of sialidase

BACKGROUND

Ureaplasma, a genus of the order Mycoplasmatales and commonly grouped with Mycoplasma as genital mycoplasma is one of the most common microbes isolated from women with infection/inflammation-associated preterm labor (PTL). Mycoplasma spp. produce sialidase that cleaves sialic acid from glycans of vaginal mucous membranes and facilitates adherence and invasion of the epithelium by pathobionts, and dysregulated immune response. However, whether Ureaplasma species can induce the production of sialidase is yet to be demonstrated. We examined U. parvum-infected vaginal epithelial cells (VECs) for the production of sialidase and pro-inflammatory cytokines.

METHODS

Immortalized VECs were cultured in appropriate media and treated with U. parvum in a concentration of 1 × 10⁵ DNA copies/ml. After 24 h of treatment, cells and media were harvested. To confirm infection and cell uptake, immunocytochemistry for multi-banded antigen (MBA) was performed. Pro-inflammatory cytokine production and protein analysis for sialidase confirmed pro-labor pathways.

RESULTS

Infection of VECs was confirmed by the presence of intracellular MBA. Western blot analysis showed no significant increase in sialidase expression from U. parvum-treated VECs compared to uninfected cells. However, U. parvum infection induced 2-3-fold increased production of GM-CSF (p = 0.03), IL-6 (p = 0.01), and IL-8 (p = 0.01) in VECs compared to controls.

CONCLUSION

U. parvum infection of VECs induced inflammatory imbalance associated with vaginal dysbiosis but did not alter sialidase expression at the cellular level. These data suggest that U. parvum's pathogenic effect could be propagated by locally produced pro-inflammatory cytokines and, unlike other genital mycoplasmas, may be independent of sialidase.

Modeling ascending Ureaplasma parvum infection through the female reproductive tract using vagina-cervix-decidua-organ-on-a-chip and feto-maternal interface-organ-on-a-chip

Genital mycoplasmas can break the cervical barrier and cause intraamniotic infection and preterm birth. This study developed a six-chamber vagina-cervix-decidua-organ-on-a-chip (VCD-OOC) that recapitulates the female reproductive tract during pregnancy with culture chambers populated by vaginal epithelial cells, cervical epithelial and stromal cells, and decidual cells. Cells cultured in VCD-OOC were characterized by morphology and immunostaining for cell-specific markers. We transferred the media from the decidual cell chamber of the VCD-OOC to decidual cell chamber in feto-maternal interface organ-on-a-chip (FMi-OOC), which contains the fetal membrane layers. An ascending Ureaplasma parvum infection was created in VCD-OOC. U. parvum was monitored for 48 h post-infection with their cytotoxicity (LDH assay) and inflammatory effects (multiplex cytokine assay) in the cells tested. An ascending U. parvum infection model of PTB was developed using CD-1 mice. The cell morphology and expression of cell-specific markers in the VCD-OOC mimicked those seen in lower genital tract tissues. U. parvum reached the cervical epithelial cells and decidua within 48 h and did not cause cell death in VCD-OOC or FMi-OOC cells. U. parvum infection promoted minimal inflammation, while the combination of U. parvum and LPS promoted massive inflammation in the VCD-OOC and FMi-OOC cells. In the animal model, U. parvum vaginal inoculation of low-dose U. parvum did not result in PTB, and even a high dose had only some effects on PTB (20%). However, intra-amniotic injection of U. parvum resulted in 67% PTB. We report the colonization of U. parvum in various cell types; however, inconsistent, and low-grade inflammation across multiple cell types suggests poor immunogenicity induced by U. parvum.

Vaginales Mikrobiom und Frühgeburtlichkeit

Hintergrund

Die Rate an Frühgeburten steigt weltweit an, ein bekannter Risikofaktor sind vaginale Infektionen.

Fragestellung

Welche Rolle spielen Infektionen als Ursache für Frühgeburtsbestrebungen? Wie ist das vaginale Mikrobiom in der Schwangerschaft zusammengesetzt und welche Bedeutung hat es in der Erkennung und Behandlung von Frühgeburtsbestrebungen.

Material und Methoden

Literaturrecherche in PubMed zu Infektion und Frühgeburten, frühem vorzeitigem Blasensprung und vaginalem Mikrobiom.

Ergebnisse

Die bakterielle Vaginose, eine Verminderung von Lactobacillus spp. und eine hohe Diversität von Bakterienstämmen im vaginalen Mikrobiom sind mit einem erhöhten Frühgeburtsrisiko assoziiert. Die antibiotische Therapie der bakteriellen Vaginose bei symptomatischen Schwangeren senkt das Frühgeburtsrisiko. Ein Screening asymptomatischer Schwangerer mit dem Ziel der Prävention von Frühgeburten ist derzeit nicht empfohlen. Das kindliche Mikrobiom und Immunsystem beginnt sich bereits in utero zu entwickeln, wobei Ernährung und Antibiotikaeinnahme während der Schwangerschaft eine wichtige Rolle spielen.

Schlussfolgerungen

Das vaginale Mikrobiom beeinflusst den Schwangerschaftsverlauf. Zwischen gesundem Mikrobiom und vaginaler Dysbiose kann klinisch nicht immer unterschieden werden. Mikrobiomanalysen leisten einen Beitrag zum besseren Verständnis pathologischer Veränderungen, jedoch gibt es aufgrund individueller Unterschiede keine allgemeine Definition des „gesunden Mikrobioms“.